Flea
2 of the 7 encyclopedias on this shelf carry an entry for Flea. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
fle, a small wingless insect at home on animals. The body of the flea is flat, enabling it to glide between the hairs of its host, an operation further facilitated by a smooth, hard coat of scales. A flea is a great jumper, proverbially hard to put one's finger on, and hard to hold. Some curious mind has calculated that if a boy were able to leap as far and as rapidly, in proportion to his weight, as a flea, he could hop around the world before breakfast. Fleas drop their eggs to hatch and breed usually on the floor. Carpets are especially desirable from the point of view of a flea. The larvae are scavengers. They find vegetable and animal matter in the dust. Comstock states that "of the domestic animals only the dog, cat, rabbit, pigeons, and poultry have fleas." The household flea is different from that which infests dogs and cats; but the latter also attacks persons, and is, in fact, the common flea of America. The human flea, the flea of literature, is confined chiefly to Europe. It is known to entomologists by the very suggestive name of pulex irritans. The flea is not satisfied, like a mosquito, to bite one spot and bite once, but he skips about and renews his efforts until he creates the impression that the house is full of fleas.
Collier's New Encyclopedia (1921)
a too well-known wingless insect. Pulex irritans. Though, as a rule, each species of Pulex is parasitic only on one animal, as P. canis upon the dog, P. talpæ on the mole, and P. hirundinis on the swallow, yet P. penetrans is said to be an exception, exception, and to prey on man, the dog, and the cat. The female lays in the cracks of floors or such places, a dozen of eggs, white and a little ciscous. In favorable weather they hatch in five or six days, giving exit to little footless larvæ, like small worms, first white, then reddish, which roll themselves in a circle or spiral, and move forward in a serpentine manner. In about 12 days they inclose themselves in a small silken shell, and become nymphs. After another 12 they come forth as perfect insects. The last brood of summer continues in the larval state all winter. The flea is incased in armor like a mediæval knight. It can leap 30 times its own height; it can draw with ease 80 times its own weight. A plant, Fleabane, has been said to destroy it. In Scripture, the rendering of the